1. Field of the Invention
The present invention relates to a laser machining apparatus for performing laser machining of welding, cutting, etc. by applying a laser beam on a workpiece from a machining tool, which is suitable for use in a motor vehicle manufacturing line.
2. Description of Related Art
Recently, the laser welding using a YAG laser as an optical energy supply source has increasingly been adopted especially on a motor vehicle manufacturing line. The reason for this is that the laser welding has an advantage of achieving high rigidity and lightweight easily in terms of vehicle body design over the spot welding.
Regarding the positioning of a machining tool that applies a laser beam on a workpiece, the use of a special positioning device and a robot capable of programing a travel path has already been proposed. Also, an example in which a line configuration such that a plurality of laser generators are prepared, and laser beams are supplied to a plurality of locations where welding is performed is considered (Japanese Patent Laid-Open Publication No. 4-238689) has been reported.
A problem associated with such laser welding and laser cutting is that in case of failure or damage to the laser generator or a fiber-optic cable used for optical transmission from the laser generator to the machining tool, even if a part thereof fails or is damaged, the manufacturing line must be stopped for a long period of time, resulting in a decrease in the rate of operation of the line.
For example, in the case where three laser generators are prepared and a laser beam is supplied from each of the laser generators to each of three machining tools to perform automatic welding at three places, in the present situation, even if any trouble occurs in one of the laser generators or one (one system) fiber-optic cable, all welding operations at three places (systems) have to be stopped to repair the system.
An object of the present invention is to avoid long-term shutdown of a machining operation and thereby increase a rate of operation even when any trouble such as failure and damage occurs partially in a system constituting a machining apparatus. Another object of the present invention is to effect an environmental separation for a laser generator liable to be affected by an harsh environment of a place where machining is done, and thereby to assist the improvement in the rate of operation from the viewpoint of environment.
In the laser beam machining apparatus in accordance with the present invention, a plurality of laser generators are arranged, one or more machining tools and machining tool moving means for supporting the machining tool are provided, and each machining tool is associated with two or more of the laser generators to form a group.
According to a first aspect of the present invention, for each group, a plurality of fiber-optic cable switching devices are provided between the laser generators and the machining tool in the group, and each of the laser generators is connected to one of the fiber-optic cable switching devices via a fiber-optic cable. Further, a connection between the fiber-optic cable switching devices and a connection between the fiber-optic cable switching device and the machining tool are made by one or more fiber-optic cables. By issuing a switchover command to the fiber-optic cable switching device, the laser generator for use and the fiber-optic cable for guiding a laser beam to the machining tool can be changed over.
Also, according to a second aspect of the present invention, one or more fiber-optic cable switching devices are arranged along a laser beam transmission path between the laser generators and the machining tool in each group.
All of the laser generators in the group are connected to one fiber-optic cable switching device arranged most upstream in the laser beam transmission path, and a connection between the fiber-optic cable switching devices and a connection between the fiber-optic cable switching device and the machining tool are made by one or more fiber-optic cables. By issuing a switchover command to the fiber-optic cable switching device, the laser generator for used and the fiber-optic cable for guiding a laser beam to the machining tool can be changed over.
In the arrangements according to the first or second aspect, it is preferable that when a trouble occurs in the laser generator, a switchover command is issued to the fiber-optic cable switching device so that the fiber-optic cable connected with the laser generator in trouble is switched to the fiber-optic cable connected with another laser generator, thereby the laser generator for use is changed over.
Likewise, in the arrangements according to the first or second aspect, it is preferable that a fiber-optic cable in trouble is switched to another fiber-optic cable in the plurality of fiber optic cables for connecting the fiber-optic cable switching device to the machining tool by a switchover command issued to the fiber-optic cable switching device.
Also, it is preferable that one of the fiber-optic cables which are respectively connected with the laser generators is selected in accordance with cutting or welding to be performed by the machining tool by a switchover command issued to the fiber-optic cable switching device.
Further, the laser generators may be arranged in an environment where at least one of temperature, humidity, cleanness and vibration is controlled and the environment of a location where the laser generators are arranged may be separated form an environment in the other locations including a location where one or more machining tools and the machining tool moving means are arranged, to thereby prevent undesirable influence on the laser generators from the environment of the other locations.
In this case, it is preferable that the separation of the environment of the location where said plurality of laser generators are arranged from the environment of the other location is performed by a separation means surrounding at least a part of the laser generators, and the separation means is formed of a laser-beam untransparent material.
Also, it is preferable to provide a detector for detecting at least one environmental factor of temperature, humidity, cleanness and vibration in the separated environment of the laser generators, and a display device for displaying a level of the environmental factor detected by the detector.
In this case, the laser machining may be stopped immediately or after elapsing a predetermined time when the detected level deviates form a predetermined range, and information regarding a cause of the stoppage of the laser machining may be displayed by the display device. It is preferable that the predetermined time is adjustable.